1、通过引入版本戳(stamp)机制解决ABA问题：
- 每次修改时递增版本号
- 执行CAS时同时检查值和版本号
- 即使值相同但版本不同，操作也会失败
2、具体代码实现
import java.util.concurrent.atomic.AtomicStampedReference;public class AtomicStampedReferenceDemo {// 账户余额初始值为100，版本号初始为0private static final AtomicStampedReference<Integer> accountBalance =new AtomicStampedReference<>(100, 0);public static void main(String[] args) throws InterruptedException {System.out.println("============== AtomicStampedReference解决ABA问题 ==============");System.out.println("初始账户余额: " + accountBalance.getReference() +"元, 版本号: " + accountBalance.getStamp());System.out.println();// 创建ABA操作线程Thread abaThread = new Thread(() -> {int[] stampHolder = new int[1];int currentValue;// 第一次修改：100 → 50System.out.println(stampHolder[0]);currentValue = accountBalance.get(stampHolder);int currentStamp = stampHolder[0];System.out.println("[ABA线程] 读取余额: " + currentValue + "元, 版本: " + currentStamp);boolean success = accountBalance.compareAndSet(currentValue,50,currentStamp,currentStamp + 1);System.out.println("[ABA线程] 修改余额为50元: " + (success ? "成功" : "失败") +", 新版本: " + accountBalance.getStamp());System.out.println("当前余额: " + accountBalance.getReference() + "元");System.out.println();// 第二次修改：50 → 100currentValue = accountBalance.get(stampHolder);currentStamp = stampHolder[0];System.out.println("[ABA线程] 读取余额: " + currentValue + "元, 版本: " + currentStamp);success = accountBalance.compareAndSet(currentValue,100,currentStamp,currentStamp + 1);System.out.println("[ABA线程] 恢复余额为100元: " + (success ? "成功" : "失败") +", 新版本: " + accountBalance.getStamp());System.out.println("当前余额: " + accountBalance.getReference() + "元");System.out.println();});// 创建转账线程Thread transferThread = new Thread(() -> {int[] stampHolder = new int[1];int currentValue = accountBalance.get(stampHolder);int currentStamp = stampHolder[0];System.out.println("[转账线程] 读取余额: " + currentValue + "元, 版本: " + currentStamp);System.out.println("[转账线程] 开始处理转账...");try {// 模拟处理耗时Thread.sleep(2000);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("[转账线程] 转账处理完成，尝试更新账户");// 尝试更新余额（增加50元）boolean success = accountBalance.compareAndSet(currentValue,currentValue + 50,currentStamp,currentStamp + 1);System.out.println("\n===== 转账操作结果 =====");System.out.println("操作结果: " + (success ? "成功" : "失败"));System.out.println("预期版本: " + currentStamp + ", 实际版本: " + accountBalance.getStamp());System.out.println("预期余额: " + currentValue + "元, 当前余额: " + accountBalance.getReference() + "元");System.out.println("=====================\n");});// 启动线程transferThread.start();Thread.sleep(500); // 确保转账线程先读取初始值abaThread.start();// 等待线程完成abaThread.join();transferThread.join();System.out.println("\n最终账户余额: " + accountBalance.getReference() + "元, 版本号: " + accountBalance.getStamp());System.out.println("============== 演示结束 ==============");}
}
============== AtomicStampedReference解决ABA问题 ==============
初始账户余额: 100元, 版本号: 0[转账线程] 读取余额: 100元, 版本: 0
[转账线程] 开始处理转账...
0
[ABA线程] 读取余额: 100元, 版本: 0
[ABA线程] 修改余额为50元: 成功, 新版本: 1
当前余额: 50元[ABA线程] 读取余额: 50元, 版本: 1
[ABA线程] 恢复余额为100元: 成功, 新版本: 2
当前余额: 100元[转账线程] 转账处理完成，尝试更新账户===== 转账操作结果 =====
操作结果: 失败
预期版本: 0, 实际版本: 2
预期余额: 100元, 当前余额: 100元
=====================最终账户余额: 100元, 版本号: 2
============== 演示结束 ==============Process finished with exit code 0
